This invention relates generally to vapor compression air conditioning systems. More particularly, the invention relates to an arrangement and configuration of the components in an air conditioner of the type commonly mounted in the window of a room.
The fundamental principles of the operation and construction of vapor compression air conditioning systems are well known in the art. In the typical window room air conditioner, all the components of the system are contained in a single enclosure. The enclosure has an inside section containing the inside refrigerant-to-air heat exchanger and an inside fan for circulating air from the room to be cooled or heated over that heat exchanger. The enclosure also has an outside section. The enclosure is configured so that air cannot pass between the inside section and the outside section. The outside section of the enclosure contains the outside refrigerant-to-air heat exchanger, an outside fan for circulating outside air over that heat exchanger and, usually, the system compressor. Other system components, such as an expansion device, controls and the like are located in either one section or the other as appropriate or desirable. The air conditioner is mounted in a window or other aperture in a wall of a room so that the inside section is inside the room and the outside section extends into the space outside the room. If the air conditioner is designed for cooling only, the outside refrigerant-to-air heat exchanger functions only as a condenser and the inside refrigerant-to-air heat exchanger operates only as an evaporator. If the air conditioner is designed for both heating and cooling, i.e. as a heat pump, a given heat exchanger may function as either a condenser or an evaporator depending on system operating mode.
Designers and builders of room air conditioners are constantly striving to increase the capacity and efficiency and reduce the size and cost of their products. One benefit of reducing the size, particularly the height, of a room air conditioner intended to be mounted in a window is that a lower profile machine occupies less of the total area of the window aperture and thus leaves more of that area available for light transmission and viewing.
Room air conditioners are commonly configured so that both the outside and the inside fans are mounted on a single shaft driven by a single motor. The motor shaft is parallel to the enclosure base and extends into both the inside and outside sections. This configuration has cost benefits but, because an axial flow fan is the most effective type of fan for use in the outside section, imposes a practical lower limit on the enclosure height of an air conditioner of a given configuration and capacity. This limit arises because of the need to provide a given minimum air flow across the outside refrigerant-to-air heat exchanger. Because of the fan motor and shaft configuration, the plane of rotation of the outside fan must be perpendicular to the enclosure base. And there is a practical upper limit on fan speed because of physical limitations and noise considerations. All of these factors dictate that the outside fan have a minimum diameter to provide the requisite air flow and that therefore the height of the enclosure be sufficient to enclose this minimum diameter.
When ambient conditions require that an air conditioning system operate in the cooling mode, the warm ambient air is frequently also humid. As the air to be cooled passes over the inside refrigerant-to-air heat exchanger, the air temperature is lowered to below the dewpoint, moisture in the air condenses as water on the heat exchanger and the condensate water drains from the heat exchanger. Some means must be provided to dispose of the condensate water. One means of disposal is to provide a condensate drain line out of the air conditioner. That approach is simple and direct but can also be inconvenient, complicated and unsightly, particularly in a small room air conditioner. Another disposal means is to provide a drainage path from the point of condensate collection under the inside refrigerant-to-air heat exchanger to a point in the outside section of the air conditioner where some means is provided to pick up and sling the condensate water on to the outside refrigerant-to-air heat exchanger. As that heat exchanger is operating as a condenser when in the cooling mode, it is warm and water impinging on it will evaporate and be carried away as vapor in the air stream passing through the heat exchanger. In addition to eliminating the need for an external condensate drain, this method of disposing of condensate also contributes to system efficiency, as the transfer of the heat of vaporization to the water contributes to the cooling of the refrigerant in the heat exchanger. In a heat pump type air conditioner, providing means for disposal of condensate on the outside heat exchanger by this means is rarely necessary.